The invention relates to prosthetic devices and, in particular, to a quadriceps control device for a prosthetic leg assembly. The invention may also be adapted for use with orthotics.
The quadriceps muscles are the large powerful muscles that produce approximately 80% of the total extension power of the human knee. The quadriceps muscles unite to form a strong tendon that attaches under the patella or kneecap. This is one of the reasons why it is so difficult for amputees having amputations above the knee. The loss of the knee joint also results in the loss of the lower attachment of the quadriceps muscle group that is utilized to extend the knee. The hamstring muscles are the knee flexor group; that is, these muscles flex the human knee. However, the quadriceps muscles also control knee flexion by a lengthening or eccentric muscle contracture.
Many users of prosthetic leg assemblies, both above and below the knee, as well as many of those requiring the use of an orthotic leg assembly, encounter difficulties controlling knee extension and flexion due, for example, to muscle weakness, nerve damage, or debilitating disease. Thus, it would be advantageous to provide a device that could to some degree mimic the quadriceps muscle group in human anatomy, to thereby enhance the ability of a user of a prosthetic or orthotic leg assembly to control knee extension and flexion.